427 research outputs found
Bisimple monogenic orthodox semigroups
We give a complete description of the structure of all bisimple orthodox
semigroups generated by two mutually inverse elements
SAFT-UT utilities: Reference manual
This manual is intended to give the user a complete command and operation reference for using the SAFT-UT utilities in the VMS environment. It augments two additional documents, the Guide to SAFT-UT Principles and Conventions and the Interface and Installation Guide. An understanding of the contents of the Guide to SAFT-UT Principles and Conventions is a recommended prerequisite to the use of the SAFT-UT utility programs
Effective theory for wall-antiwall system
We propose a useful method for deriving the effective theory for a system
where BPS and anti-BPS domain walls coexist. Our method respects an
approximately preserved SUSY near each wall. Due to the finite width of the
walls, SUSY breaking terms arise at tree-level, which are exponentially
suppressed. A practical approximation using the BPS wall solutions is also
discussed. We show that a tachyonic mode appears in the matter sector if the
corresponding mode function has a broader profile than the wall width.Comment: LaTeX file, 30 page, 5 eps figures, references adde
Lattice isomorphisms of bisimple monogenic orthodox semigroups
Using the classification and description of the structure of bisimple
monogenic orthodox semigroups obtained in \cite{key10}, we prove that every
bisimple orthodox semigroup generated by a pair of mutually inverse elements of
infinite order is strongly determined by the lattice of its subsemigroups in
the class of all semigroups. This theorem substantially extends an earlier
result of \cite{key25} stating that the bicyclic semigroup is strongly lattice
determined.Comment: Semigroup Forum (published online: 15 April 2011
Stony coral populations are more sensitive to changes in vital rates in disturbed environments
Greenland Blocking Index 1851-2015: a regional climate change signal
We present an extended monthly and seasonal Greenland Blocking Index (GBI)
from January 1851- December 2015, which more than doubles the length of the existing
published GBI series. We achieve this by homogenising the Twentieth Century Reanalysis
version 2c-based GBI and splicing it with the NCEP/NCAR Reanalysis-based GBI. For the
whole time period there are significant decreases in GBI in autumn, October and November,
and no significant monthly, seasonal or annual increases. More recently, since 1981 there are
significant GBI increases in all seasons and annually, with the strongest monthly increases in
July and August. A recent clustering of high GBI values is evident in summer, when seven
out of the top eleven values in the last 165 years – including the two latest years 2014 and
2015 - occurred since 2007. Also, 2010 is the highest GBI year in the annual, spring, winter
and December series but 2011 is the record low GBI value in the spring and April series.
Moreover, since 1851 there have been significant increases in GBI variability in May and
especially December. December has also shown a significant clustering of extreme high and
low GBI values since 2001, mirroring a similar, recently identified phenomenon in the
December North Atlantic Oscillation index, suggesting a related driving mechanism. We
discuss changes in hemispheric circulation that are associated with high compared with low GBI conditions. Our GBI time series should be useful for climatologists and other scientists interested in aspects and impacts of Arctic variability and change
The algebra of adjacency patterns: Rees matrix semigroups with reversion
We establish a surprisingly close relationship between universal Horn classes
of directed graphs and varieties generated by so-called adjacency semigroups
which are Rees matrix semigroups over the trivial group with the unary
operation of reversion. In particular, the lattice of subvarieties of the
variety generated by adjacency semigroups that are regular unary semigroups is
essentially the same as the lattice of universal Horn classes of reflexive
directed graphs. A number of examples follow, including a limit variety of
regular unary semigroups and finite unary semigroups with NP-hard variety
membership problems.Comment: 30 pages, 9 figure
A Comparison of the Technical Communications Practices of Japanese and U.S. Aerospace Engineers and Scientists
To understand the diffusion of aerospace knowledge, it is necessary to understand the communications practices and the information-seeking behaviors of those involved in the production, transfer, and use of aerospace knowledge at the individual, organizational, national, and international levels. In this paper, we report selected results from a survey of Japanese and U.S. aerospace engineers and scientists that focused on communications practices and information-seeking behaviors in the workplace. Data are presented for the following topics: importance of and time spent communicating information, collaborative writing, need for an undergraduate course in technical communications, use of libraries, the use and importance of electronic (computer) networks, and the use and importance of foreign and domestically produced technical reports. The responses of the survey respondents are placed within the context of the Japanese culture. We assume that differences in Japanese and U.S. cultures influence the communications practices and information-seeking behaviors of Japanese and U.S. aerospace engineers and scientists
Possible Supersymmetric Effects on Angular Distributions in Decays
We investigate the angular distributions of the rare B decay, , in general supersymmetric extensions of the standard
model. We consider the new physics contributions from the operators
in small invariant mass region of lepton pair. We show that the
azimuthal angle distribution of the decay can tell us the new physics effects
clearly from the behavior of the distribution, even if new physics does not
change the decay rate substantially from the standard model prediction
New single-ended objective measure for non-intrusive speech quality evaluation
peer-reviewedThis article proposes a new output-based method for non-intrusive assessment of speech quality of voice communication systems and evaluates its performance. The method requires access to the processed (degraded) speech only, and is based on measuring perception-motivated objective auditory distances between the voiced parts of the output speech to appropriately matching references extracted from a pre-formulated codebook. The codebook is formed by optimally clustering a large number of parametric speech vectors extracted from a database of clean speech records. The auditory distances are then mapped into objective Mean Opinion listening quality scores. An efficient data-mining tool known as the self-organizing map (SOM) achieves the required clustering and mapping/reference matching processes. In order to obtain a perception-based, speaker-independent parametric representation of the speech, three domain transformation techniques have been investigated. The first technique is based on a perceptual linear prediction (PLP) model, the second utilises a bark spectrum (BS) analysis and the third utilises mel-frequency cepstrum coefficients (MFCC). Reported evaluation results show that the proposed method provides high correlation with subjective listening quality scores, yielding accuracy similar to that of the ITU-T P.563 while maintaining a relatively low computational complexity. Results also demonstrate that the method outperforms the PESQ in a number of distortion conditions, such as those of speech degraded by channel impairments.acceptedpeer-reviewe
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